Snow Extent Variability in Lesotho Derived from MODIS Data

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by: Stefan Wunderle, Timm Gross and Fabia Husler

Abstract

In Lesotho, snow cover is not only highly relevant to the climate system, but also affects socio-economic factors such as water storage for

irrigation or hydro-electricity. However, while sound knowledge of annual and inter-annual snow dynamics is strongly required by local

stakeholders, in-situ snow information remains limited. In this study, satellite data are used to generate a time series of snow cover and to

provide the missing information on a national scale. A snow retrieval method, which is based on MODIS data and considers the concept of a

normalized difference snow index (NDSI), has been implemented. Monitoring gaps due to cloud cover are filled by temporal and spatial

post-processing. The comparison is based on the use of clear sky reference images from Landsat-TM and ENVISAT-MERIS. While the snow product is

considered to be of good quality (mean accuracy: 68%), a slight bias towards snow underestimation is observed. Based on the daily product, a

consistent time series of snow cover for Lesotho from 2000–2014 was generated for the first time. Analysis of the time series showed that the

high annual variability of snow coverage and the short duration of single snow events require daily monitoring with a gap-filling procedure. V


Keywords: snow cover; MODIS; NDSI; Lesotho; temporal and spatial gap-filling

Link to website: http://www.mdpi.com/2072-4292/8/6/448

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